SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae68c34410372b6dc8e1a3a42e7f0bc2413fafc5215b9ffc2a76926ee2f51d98' 
  AND token = 'wRVj3Xoqpk+g4UUPH/ObQjwIJKxOxSkQYofvSJZIQTQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}